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The problem of damage assessment in dam structures is addressed: the aim is to employ a system identification technique (Kalman Filter) and determine unknown elastic constants, whose values can be related to the current structural conditions and can be interpreted as ‘indicators’ of degradation phenomena. Namely, the final objective is the estimate of pairs of parameters (bulk modulus and shear modulus) in critical zones, where material properties might be affected by damage processes: the use of both moduli is justified by the fact that structural damage is often due to the combined action of isotropic and deviatoric stress components, as explained by various theoretical models. After giving some basic information about the proposed method, we briefly discuss numerical simulations, which show that the Kalman Filter can be conveniently exploited to detect areas where damage has occurred and/or is spreading and/or is likely to be present.

The paper focuses on the estimate of stiffness parameters concerned with large dams. Experimental records taken during shaking tests and/or micro-seismic activity are assumed as input data and the Kalman filtering approach is applied in order to determine optimal values of unknown elastic constants. The subject is related to the issue of monitoring, since possible changes of elastic properties can be interpreted as “indicators” of ongoing deterioration processes. The method has been implemented with the aim of estimating pairs of parameters (bulk modules and shear modules). In this way it is possible to consider undesired effects due to isotropic and deviatoric stress components, in accordance to the theoretical framework upon which several damage models are based. Numerical simulations show that the technique discussed in the paper is suitable to detect a decrease of mechanical properties if adequate tests are carried out at regular intervals.

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2-(Azidomethyl)phenyl isocyanide, 2-(CH2N3) C6H4N?C (AziNC), coordinates to some cationic Pt(II) and Pd(II) species to afford isocyanide complexes of the type trans-[MCl(AziNC)(PPh3)2][BF4] (M=Pt, l; Pd, 2). AziNC is coordinated also in some neutral Pt(II) and Pd(II) species such as [MCl2(AziNC)2] (M=Pt, 3; Pd, 4) derived from the reactions of 2? of AziNC with [PtCl2(COD)] and [PdCl2(MeCN)2], respectively. Complexes 1 and 2 react with 1? of PPh3 affording the heterocyclic carbene complexes trans-[MCl{CN(H)} (PPh3)2][BF4] (M=Pt, 5; Pd, 6). Complexes 3 and 4 react with 1? of PPh3 displacing the isocyanide with the formation of the complexes cis-[MCl2 (AziNC)(PPh3)] (M=Pt, 7; Pd, 8. These latter ones react with 2 equiv. of PPh3 affording as the final products the cationic carbene species trans-[MCl{CN(H)}(PPh3)2][Cl] (M=Pt, 9; Pd, 10). Complex 5 was also characterized by single crystal X-ray diffraction. The carbene complex is square-planar and the angle formed between the platinum square plane and the heterocyclic carbene ligand is 87.9(2)°. The C(1)-N(1) and C(1)-N(2) bond distances in the latter of 1.32(2) and 1.30(2) Å, respectively, are short for a single bond and indicate extensive ?-bonding between the nitrogen atoms and the carbene carbon.

In this article the application of the sol-gel technique to phosphazene substrates to obtain a novel series of hybrid materials is revieved. Different types of phosphazenes are suitable for this goal, i.e. hexachlorocyclophosphazene and polydichlorophosphazene, alkoxy-substituted phosphazene substrates, phosphazene polymers bearing oligoethyleneoxyde or trifluoroethoxide moieties, phosphazene derivatives containg alkoxy or aryloxy groups functionalized with free hydroxyl functions, and cyclophosphazenes containing trialcoxysilane functionalities. For some of these materials only weak forces are involved between phosphzenes and the inorganic network ehen hybrid materialss are prepared. For others genuine chemical bonds are formed among them. In both cases relevant improvments for the applicability properties of phosphazene substrates are observed together with the onset of new features